# Perl Code fragment to decode the ASCII %XX hex characters
# that are passed to the CGI script by many browsers for
# special characters such as ";"

$_ = $arg;
tr/+?/  /;
s/%([0-9a-fA-F]{2})/pack('H2',$1)/ge;	# decode %xx
die if m/[^a-zA-Z0-9 ,_-]/;		# check for invalid chars
return $_;